The present invention relates to methods and apparatuses for transporting a flow of air and particulates through a vacuum cleaner.
Conventional upright vacuum cleaners are commonly used in both residential and commercial settings to remove dust, debris and other particulates from floor surfaces, such as carpeting, wood flooring, and linoleum. A typical conventional upright vacuum cleaner includes a wheel-mounted intake nozzle positioned close to the floor, a handle that extends upwardly from the nozzle so the user can move the vacuum cleaner along the floor while remaining in a standing or waling position, and a blower or fan. The blower takes in a flow of air and debris through the intake nozzle and directs the flow into a filter bag which traps the debris while allowing the air to pass out of the vacuum cleaner.
One drawback with some conventional upright vacuum cleaners is that the flow path along which the flow of air and particulates travels may not be uniform and/or may contain flow obstructions. Accordingly, the flow may accelerate and decelerate as it moves from the intake nozzle to the filter bag. As the flow decelerates, the particulates may precipitate from the flow and reduce the cleaning effectiveness of the vacuum cleaner. In addition, the flow obstructions can reduce the overall energy of the flow and therefore reduce the capacity of a flow to keep the particulates entrained until the flow reaches the filter bag.
Another drawback with some conventional upright vacuum cleaners is that the blowers can be noisy. For example, one conventional type of blower includes rotating fan blades that take in axial flow arriving from the intake nozzle and direct the flow into a radially extending tube. As each fan blade passes the entrance opening of the tube, it generates noise which can be annoying to the user and to others who may be in the vicinity of the vacuum cleaner while it is in use.
Still another drawback with some conventional upright vacuum cleaners is that the filter bag may be inefficient. For example, some filter bags are constructed by folding over one end of an open tube of porous filter material to close the one end, and leaving an opening in the other end to receive the flow of air and particulates. Folding the end of the bag can pinch the end of the bag and reduce the flow area of the bag, potentially accelerating the flow through the bag. As the flow accelerates through the bag, the particulates entrained in the flow also accelerate and may strike the walls of the bag with increased velocity, potentially weakening or breaking the bag and causing the particulates to leak from the bag.
The invention relates to methods and apparatuses for filtering a flow of air and particulates in a vacuum cleaner. In one embodiment, the apparatus can include a removable vacuum cleaner filter having a flange portion with a flange aperture therethrough and a flexible, porous filter element portion attached to the flange portion. The filter element portion can be elongated along a filter axis and can have an opening generally aligned with the flange aperture. The filter element has a generally constant cross-sectional area when intersected by a plane generally perpendicular to the filter axis. In one aspect of this embodiment, the filter element has an upper portion and a lower portion below the upper portion and the opening of the filter element is in the upper portion so that the flow of air and particulates is directed into the filter from above. The filter element portion can include paper or fabric material and can have a generally rectangular cross-sectional shape with rounded corners.